The invention relates to a casing for a drive unit, which consists of a base body with at least one depression for the accommodation of drive elements.
Such types of casings are used, in particular, in automobile assembly, among other areas, for operating wiper devices.
The casing is generally constructed of metal, in order to give it a sufficient strength.
The invention is based upon the task of further developing such a type of casing in such a manner that it has, on the one hand, only a slight weight and, on the other hand, has a rigidity which is sufficient to be able to support the forces which are brought about. It is thus proposed that the base body of the casing be produced of plastic reinforced by glass fiber, and that a depression in the casing, which [depression] accommodates the drive elements, be sealed by means of a metallic cover unit.
A drive shaft is conducted through the base of this casing to the exterior. Since considerable pitching moments are exerted on this shaft, particularly if it serves for the driving of a wiper arm, a correspondingly long guide unit is necessary. In order to securely anchor this guide unit within the casing, it is proposed that a peg accommodation mount, which rises vertically out of the base, be positioned in the base of the depression; and that the guide casing (or bearing sleeve), which likewise extends vertically outwardly to the base of the base body, be constructed on the base body; and that reinforcement struts proceed between the peg accommodation mount and the guide casing.
One particularly stable and yet light construction anchoring of the guide casing is achieved if the guide casing is positioned in a dome unit, whereby reinforcement struts proceeding perpendicularly are positioned between the internal walls of the dome unit and the external walls of the guide casing.
Metallic conducting strips, which are stamped from a grid, can be inserted into the base of such a type of casing.
In order to be able to attach such types of grids to the plastic, it is known to provide pegs, which are conducted through corresponding holes in the grid, projecting vertically out in the plastic. These pegs can be later pressed down by means of a heat stamp, whereby the melting plastic is applied over the lattice in a knob-like manner.
It has been shown that this method can simply not be used with plastic reinforced by means of glass fiber, since the glass fibers can not be pressed down by a heat stamp. For the attachment of a metal sheet to a base body of plastic reinforced by glass fiber, it is thus proposed that single-part pegs be integrally formed on the base body, and that the metal grid have penetrating apertures, the internal diameter of which are somewhat smaller than the diameter of the pegs, whereby the penetrating apertures can be formed in the metal grid proceeding in a conical manner. In this way, the metal grid engages with the pegs, since the edge of the penetrating apertures is applied, in a manner similar to a barb, against the wall of the peg.
This method of attachment is entirely suited for attaching thin metal sheets to support parts which consist, above all, of plastic reinforced by glass fiber.